The development of the VSE was a direct outgrowth of the devastating loss of the Shuttle Columbiaand its crew of seven on February 1, 2003. When questions arose over the need for a human space program, members of the Bush administration undertook a year-long internal study on the purpose and direction of America’s civil space effort. Why do we send people into space? What are our ultimate goals? Many options were on the table during this period of soul-searching.

Post-Columbia, it was very apparent to those who knew and understood the numbers that regardless of direction, significant increases in NASA’s funding were not likely. Any new mission would have to fit an essentially no-growth agency budget (with two wars raging and the explosive growth of entitlement spending, the federal budget could not be stretched enough to cover a doubling of the agency budget – which even if possible, was less in real dollars than Apollo had 40 years earlier). Thus the question became: Given that additional new money would be extremely limited, how can we safely move beyond low Earth orbit? The answer was to maximize our access to space by learning how to use what is available in space to create new capability.

A chemical-propulsion human mission to Mars might have a total mass in Earth orbit of some 500 tons; more than 80% of that mass is fuel for the journey. There are two ways to lower the costs of such a mission: 1) significantly lower the costs of launch from Earth; 2) identify and make fuel from mining sites in space. We’ve struggled off and on with the former but have never attempted the latter. Moreover, learning how to use the resources of space is an essential skill to master for long term, sustainable human presence in space.

The speech Marburger gave at that symposium stands today as one of the clearest and most “visionary” articulations of a future in space ever given.

The Vision for Space Exploration (VSE) was unveiled at NASA headquarters by President Bush. The January 2004 mission announcement was groundbreaking in that the President identified the use of lunar resources to help create and advance a sustainable human presence, specifically, the production of fuel from lunar materials for beyond LEO missions. It was the first time such a concept had been mentioned in any policy declaration. Subsequently, that part of Bush’s speech was proclaimed by many commenting on, or working for the space community, as meaning “building the Mars ship on the Moon.” That characterization confused the clear message that had been sent – one of using what is in space (resources) to create new space faring capabilities (product) starting on the Moon.

Jack Marburger was deeply involved in the year-long space policy study and it was clear that his insight and vision were more acute than many others working in the White House and at NASA. I remember meeting with him in his office at OSTP in mid-2004, some months after the VSE had been announced. At that time, he was aware of the concept of using space resources and was still formulating the implications and possibilities of such an activity. We discussed the idea of water as the “currency” of spaceflight, being useful for life-support consumables, energy storage and rocket fuel. I described for him our then-current knowledge (which at the time was extremely meager but promising) of the presence of ice at the poles of the Moon and the likelihood that appreciable quantities of water might be harvested there.

In the spring of 2006, Jack gave a keynote address at the 44th Goddard Space Symposium. In his speech he pointedly asked, “Why do we have a space program?” Rather than repeating the usual clichés about exploring the unknown or inspiring the next generation, Jack articulated a clear policy direction by saying, “questions about the Vision boil down to whether we want to incorporate the Solar System in our economic sphere, or not.” He specifically noted that such a motivation is vastly different from the one that propelled America to the Moon in the 1960s, saying, “The Moon has unique significance for all space applications for a reason that to my amazement is hardly ever discussed in popular accounts of space policy.” The Moon is the nearest, most accessible useful object beyond low Earth orbit and that is why it is the first step of the VSE. We go to the Moon not to repeat Apollo but to create new capability. Jack understood this clearly.

The speech Marburger gave at that symposium stands today as one of the clearest and most “visionary” articulations of a future in space ever given. It was nothing less than the declaration of a new paradigm for spaceflight, one in which we go and do in space whatever jobs we can imagine or need. This capability is created by learning to use what we find in space, reducing the need to launch (at such prohibitive cost) everything from the bottom of the deepest gravity well in the inner Solar System. As long as we are held hostage to this old template, we will always be mass- and power-limited in space and thus limited in capability.

Jack Marburger understood the importance of and need for human exploration. He sought innovative ways to create a sustainable and affordable space program. Those of us who believe in this vision note his passing with sadness, but also with renewed determination to pursue this viable path. We honor his memory and salute his contributions.

Fresh impact crater ejecta is generally brighter than the surroundings because it is "immature". As material rests on the surface of the Moon it is slowly altered by solar wind sputtering and micrometeorite bombardment that results in a general darkening and shift in color.

This change in reflectance properties is known as space weathering, or maturation. Impacts excavate materials from beneath the mature surface resulting high reflectance rays. If you are very patient, and waited around for 500 million years you could observe rays slowing fade as they mature. But the small crater (25 meter diameter) in today's Featured Image displays dark ejecta deposits, so what is happening here?

Ejecta blanket at north of the rim (lower left) of Censorinus A. field of view 2.3 km, nearly the full width of LROC NAC M1144409490L. The white rectangle indicates the area of within the LROC Featured Image, July 28, 2011. [NASA/GSFC/Arizona State University].

This tiny crater is located near near Mare Tranquillitatis, 3 km north of the rim of Censorinus A crater. The surrounding area is covered by ejecta coming from Censorinus, which is about 12 km distant (the surface streaks point back to the crater). The dark and bright areas are intermixed (see middle image), and the tiny dark ejecta crater is located on the brighter portion of the ejecta. The brighter ray materials are likely on the top of darker materials, which are perhaps simply mature soils or maybe impact melt from the earlier Censorinus impact event. So when the small crater was formed, it excavated dark material from beneath a bright ray.

Cape Canaveral – Apollo 15 was the first manned lunar mission to use a lunar rover, the first of the “J” missions that would stay on the lunar surface longer and be focused on conducting science. Apollo 15 marked its 40th anniversary on Sunday. Most of the crew as well as other Apollo-era astronauts were present at the Kennedy Space Center Visitor Complex to mark the occasion.

Detail from the panoramic view as captured by mission commander Dave Scott during the second EVA of the Apollo 15 science expedition to the Hadley Rille Valley (MET: 144:50:48), August 1, 1971. According to the Apollo 15 Surface Journal, "twenty years after the mission, this 500-mm photograph" was still Scott's favorite. View the high-resolution image HERE [ASJ/NASA].

Hadley Station, landing site of Apollo 15, 39 years, 4 months and 13 days later, as viewed from 43.33 kilometers overhead, in LROC Narrow Angle Camera (NAC) observation M146959973L, swept up December 14, 2010. The LM descent stage is at the center of this sample with a path leading left (eastward) to the first lunar rover of the Apollo program, where Scott & Irwin parked it 40 years ago. Their trail to the ALSEP experiments and laser reflector array can be seen on the opposite side. Lighting conditions at local sunrise were similar to those the crew experienced during their landing in 1971 [NASA/GSFC/Arizona State University].

The platy surface, partially submerged boulders and flows are an invitation to explorers!

The edges of the floor are sharply overlayed by debris avalanches from the cavity slopes. How did the flows seen on the left form? Are they impact melt or later debris flows?

Full view of the Rümker E crater floor at the full field of view width of about 2.5 km seen in LROC NAC M122591558L. The square corresponds to the LROC Featured Image released July 27, 2011. See the full-sized context image HERE [NASA/GSFC/Arizona State University].

Crater shapes are changing with time little by little, by slope failures inside the cavity, isostatic rebound, and magma intrusions (depending on the crater size). Debris flows in Rümker E will continue to mask the melt-covered floor, eventually the whole area. There are lots of degraded craters on the Moon showing no interior melt deposits, but they may be there now buried waiting for future astronauts to uncover.

Impact melts are especially interesting to geologists because they are clocks. The melting resets the internal radiometric clock so even a small sample provides the means to date the moment the impact occurred.

Today's Featured Image displays viscous flow features out of a fresh crater, likely the impact melt flows. The lower left bright portion corresponds to the crater cavity's inner slope, and the other area is outside the cavity with the slope in upper right direction.

The original source point of these flows are lost, probably due to slumping of the steep inner walls. When the rim failed and slid into the crater the head of the flows were truncated leaving a sharp edge, often with cracks parallel to the rim. Since the flows overlie the main ejecta blanket we can infer that the melt was thrown out late in the crater forming process. These cross-cutting or the overlapping relationships help scientists to understand the complicated process of impact cratering!

Small dome in the Compton-Belkovich "Thorium Anomaly" region (61.33 °N, 99.68 °E). Evidence indicates a volcanic origin for this and other intriguing features in this relatively small area in the highlands of the lunar farside's northern hemisphere. Solar illumination Incidence Angle is 64°, Sun is from the SSW, field of view roughly 510 meters. LROC Narrow Angle Camera (NAC) observation M139238146L, LRO orbit 5653, September 16, 2010. See the full-size LROC Featured Image HERE [NASA/GSFC/Arizona State University].

Same dome, early evening shadow, brings out small topographic features in relief. Note in the close-up view in the image following below the summit boulder shadows. Full frame field of view above is roughly 3100 meters across; LROC NAC observation M119198897L, LRO orbit 2700, January 27, 2010 [NASA/GSFC/Arizona State University].

Since the domes in the Compton-Belkovich area are rounded and smooth (excepting the boulders scattered across the summit) they are not easy to spot. At sunrise and sunset (above) even smooth topography casts long shadows. In this case the Sun is 13° degrees above the horizon, showing that the slopes of the dome are steeper than 13°, an important clue to unraveling its origin. Steeper slopes often mean more viscous magma, which in turn points toward more silica rich compositions.

Full-resolution close-up of Compton-Belkovich "Dome-1" from M119198897L and the early evening shadow brings the meter-sized boulders into view [NASA/GSFC/Arizona State University].

Are you having trouble seeing the feature as a dome, that is, with positive relief? Consider the above subsampled images above from M119198897L and the wider view that includes a small crater just east of the dome. The sun is from the left. Sometimes your brain can be fooled - you see what is up as what is down. If you know the Sun direction you can "force" the ups to become downs, and vice versa. And what about the little crater at the top of the dome? Is it a volcanic vent or an impact crater? If you said “impact crater” – you are right! The top of the dome is actually about 100 m south of the small crater. The crater just happens to be near the top of the dome.

LROC Wide Angle Camera (WAC) observation M119212328M, LRO orbit 2702, January 27, 2010, and a rare example of "non-mare" silicic volcanism situated between Compton and Belkovich craters on the lunar farside, the "Compton-Belkovich High-Reflectance Feature." For scale, the small dome (and it's companion crater to the east) are indicated by the yellow arrow [NASA/GSFC/Arizona State University].

Composite image showing geochemistry from Lunar Prospector and the spike in thorium coincident with the CBHRF. (Note the nearside-farside differences in thorium seen in the inset) View the full-size context composite illustration HERE [Jolliff et al, 2011].

The Compton-Belkovich site was of special interest even before the LRO mission began. Back in 1998 the Lunar Prospector spacecraft, with its gamma-ray spectrometer, measured the global distribution of the element thorium, which has a strong peak in the gamma-ray spectrum because it is naturally radioactive. Although much of the Moon’s thorium, at least as expressed on the surface, lies mostly on the nearside, a terrain between the craters Compton and Belkovich lit up like a bull’s eye (above). For this reason, the site was selected as one of NASA’s Project Constellation sites because it is of high interest for future human or robotic exploration.

This thorium “hot spot” was described by David Lawrence and the Lunar Prospector gamma-ray spectrometer team (see figure), later Jeff Gillis and coworkers noted in looking at Clementine images that a high albedo feature was located near the center of the thorium bull’s eye (see WAC context image above). However, since then, the origin of the hot spot and the nature of the deposits was not known until LRO imaged the site with the LROC Narrow Angle Cameras. Those images revealed numerous volcanic features, some large, and some small, like the little dome seen in today’s featured image. Between the Lunar Prospector and Diviner geochemistry and the LROC images, we are able to determine that these domes are examples of silicic (rich in silica relative to basalt) volcanism. An amazing discovery - the only silicic volcanism on the farside.

Be sure to return and read future posts about other features in this intriguing and unusual volcanic terrain on the Moon. What a fabulous place this would be for astronaut geologists to explore, do field geology, and collect samples for analysis!

What caused this peculiar-looking impact? The "butterfly"-shaped ejecta pattern is diagnostic of a low-angle collision (see another example here). The dark/light contrasting tones are indicative of compositional or maturity differences among the target materials (see another example here). This much we understand. But was it created by a chunk of space debris or from the crash landing of a space probe? The LROC NAC resolution is so high that small features from Apollo-era landed or crashed spacecraft are often visible. Today's Featured Image is a fitting topic for the 42nd anniversary of the Apollo 11 landing, which landed safely in Mare Tranquilitatis on July 20, 1969.

Lunar Orbiter 2 was an unmanned imaging spacecraft used in November and early December 1966 to aid with Apollo and Surveyor landing site selection. The spacecraft became famous in 1967 with the public release of an oblique image of Copernicus crater (one of only four obliques collected), which was hailed as the "Picture of the Century" by the news media of the day. According to the 2007 International Atlas of Lunar Exploration, the Lunar Orbiter 2 spacecraft was commanded to crash into the lunar farside surface on October 11, 1967. The coordinates of the Lunar Orbiter 2 impact are given as 119.1° east longitude and 3.0° north latitude, which match those of the feature in the NAC image (measured at 119.149° east longitude, and 3.020° north latitude). However, the published Lunar Orbiter 2 numbers are given as a rough estimate because the impact occurred on the farside of the Moon, out of direct radio contact. So the match with the NAC coordinates could be a coincidence. The impact appears much too large (~85 m in diameter) to be the result of an impact from a spacecraft only a few meters tall, but with a solar incidence angle of only 12 degrees, it is difficult to see the crater rim and find out the true diameter. Perhaps the ejecta pattern extends far beyond the immediate impact. The truth is that we are not sure what caused this impact feature. We are currently re-targeting the area under a higher incidence angle to help with crater rim measurements. Stay tuned!

What additional clues would you look for to satisfy this mystery? The feature is very asymmetrical. Would it help to know the orientation of Lunar Orbiter 2's final orbit? Why? Here is a good discussion for the classroom!

See if you can find the tiny feature in the full NAC image here, and look to the following Featured Image posts for additional spacecraft recovered through NAC targeting.

The Universities Space Research Association's Lunar and Planetary Institute (LPI) invites applications for lunar science and exploration postdoctoral fellowships. The opportunities include research in:

Modeling of Impact Cratering Processes - Primarily using hydrocodes and relevant analytical techniques to evaluate different types of cratering processes on the Moon, to model specific crater or basin-forming events, and potentially guide future exploration scenarios.

The successful candidates should be able to work independently, although encouraged to take advantage of the tremendous lunar-related expertise in the Houston area. The successful candidate will be a member of the LPI-JSC Center for Lunar Science and Exploration, which is one of the core teams within the NASA Lunar Science Institute.

USRA offers a competitive salary and benefits package. If there are any questions about the science involved in the position, please contact Dr. David A. Kring. Interested applicants should submit a curriculum vita with list of publications, a two to three page statement of research interests, and a list of three references to resume@lpi.usra.edu. There is no firm application deadline, although a review of applications will begin August 15, 2011.

The Universities Space Research Association is an Equal Opportunity Employer.

As space enthusiasts and students of the Solar System, we all know that the tremendous energies unleashed by a hypervelocity impact vaporize much of the impactor, fracture the target subsurface, and send cubic kilometers of pulverized and melted ejecta sailing over the horizon. When conditions are right, however, some impacts also produce strange and counter-intuitive phenomena. Dry ejecta can sometimes behave like a fluid and travel as a ground-hugging debris flow great distances from the impact site. The exact physics of this ground-hugging flow behavior is not well understood, but several theories exist. The most popular of these employs the idea of acoustic energy waves keeping particles in motion -- bouncing off each other at just the right frequencies to keep everything suspended much longer than one might anticipate. With friction reduced by this resonant internal energy, the flow can move great distances before finally losing momentum to become part of a distal ejecta deposit.

On Earth, this type of debris flow is known as a sturzstrom, most often associated with avalanches. Evidence for similar behavior is observed on the Moon in the vicinity of relatively recent craters. The odd mounds shown here were caused by the Necho impact (see context image below), and are the result of such flows bunching up and overriding each other as they slowed and came to their final resting place in nearby Necho R crater upon reaching its floor and steep southwestern wall; hence the technical term "deceleration lobes" for these landforms.

A virtual view of the same LROC WAC mosaic as an overlay upon the lunar digital elevation model available in later versions of Google Earth. Both Necho and Necho R are situated on the north wall of the much older and larger Necho P, a fact which may somewhat explain the unusual slumping seen in Necho. The scene within the LROC Featured Image released July 21, 2011 is indicated by the small arrow [NASA/GSFC/Arizona State University/JAXA/Google].

Like sand sifted through the fingers of a giant, loose debris beautifully ornaments the slopes of the Messier A crater walls. Outcropping bedrock projections stand in relief against avalanches that once flowed on either slide. Take a closer look at the outcrops in the expanded view of this image and you will see fine layering! This is yet another region of mare deposit where we see evidence for multiple, thin lava flows, now exposed in cross-section by the excavations of an impact. This fine layering is a surprise to planetary scientists - one of the many revelations about the Moon made with NAC-scale imaging.

This particular area may have captured your eye if you have ever looked at the Moon through a backyard telescope. It is visible beginning with the waxing crescent phase, and remains so until a couple days past full. Named after the 18th Century French amateur astronomer, Messier crater is located in Mare Fecunditatis (the Sea of Fertility). Its peculiar "comet-like" appearance is still somewhat mysterious to planetary scientists, but seems to have involved a complex interplay between more than one impacting object with at least one of them impacting at a highly oblique angle. The impact(s) excavated mare materials and spread them out as an extended pair of rays that stretch to the west, looking very comet-like indeed through the telescope eyepiece.

The Messier A crater region as seen through an amateur telescope of moderate power, five nights after New Moon. The unusual oblong shape of Messier, the double impact and westerly direction of the bright rays extending from Messier A seem to point to a very steep and oblique impact.

Explore the full NAC frame here. What other features can you find? Additional examples of mare layering can be found. Look for layering in the flows of Bessel crater, Linne crater and in the walls of pit craters.

A slightly different angle on the LROC WAC Global Mosaic, and take, on Messier and Messier A with west at the top reveals to the eye the distinct texture of impact melt on the floor of Messier A and the landslide region on the crater's south interior wall (to the left). Through the NAC close-up (below) the impact melt appears to harbor more than one collapse pit [NASA/GSFC/Arizona State University].

Scattered among the debris on the impact melt covering the floor of Messier A are more than a few collapse pits, to the northeast of the location of the LROC Featured Image for July 19, 2011 [NASA/GSFC/Arizona State University].

“In view of his many fundamental and far-reaching contributions to lunar science and his leadership efforts such as serving as the founding director of the Lunar Exploration Analysis Group, Dr. Taylor is exceptionally deserving of this medal,” said Yvonne Pendleton, director of the NASA Lunar Science Institute. “We are proud to present him with this honor.”

The Shoemaker Distinguished Lunar Scientist Award is an annual award given to a scientist who has significantly contributed to the field of Lunar Science throughout the course of their scientific career. The first Distinguished Lunar Scientist Award was given posthumously to Dr. Gene Shoemaker and presented to his wife Carolyn for his many contributions to the lunar geological sciences. The award was subsequently named after Dr. Shoemaker and includes a medal with the Shakespearian quote “And he will make the face of heaven so fine, that all the world will be in love with night.” Last year’s Shoemaker award was presented to Don E. Wilhelms.

An unprecedented view of the space shuttle Atlantis and the ionization of its re-entry into Earth's atmosphere, "appearing like a bean sprout against clouds and city lights," on its way home, July 21, 2011. Photographed by Expedition 28 from the ISS. Pre-dawn airglow over Earth can be seen in the background [NASA].

0957 UT, 21 July 2011: Atlantis returns to Earth for the final time, bringing an end to the program after more than thirty years, after 200 orbits and 8.5 million km. It was the 25th night landing and 78th landing at KSC, only the 133rd landing since 1981. MET: 12 days, 18 hours, 28 minutes and 50 seconds. Since April 12, 1981, 355 individuals from 16 countries flew 852 times aboard the shuttle, deploying 180 payloads, including satellites, returned 52 payloads from space and retrieved, repaired or redeployed seven spacecraft. STS-135 was the 33rd and final flight for Atlantis after totaling 307 days in space, 4,848 orbits and 872.3 million kilometers (roughly 48.49 light minutes or 5.8 AU) [NASA].

With the death of Tom Gehrels on July 11, the UA's Lunar and Planetary Lab lost a pioneer in planetary astronomy.

Raised on a farm in the Netherlands, his aspirations were focused on a career path above and beyond the fields, said his son, Neil Gehrels. During World War II, Tom Gehrels joined the Dutch Resistance against the Nazis. He eventually escaped from the country and fought again alongside the British. As a paratrooper, he dropped behind enemy lines several times. Neil Gehrels said it was during the war years that his father became interested in science and astronomy.

Initially, Gehrels' astronomy career landed him at universities across the country. It was at his final stop at the UA where he would have his biggest impact and revolutionize the way people understand and view outer space.

He arrived at the UA in 1961 as an associate professor. During nearly half a century of work with the Lunar and Planetary Lab, he made many notable contributions to the field of planetary sciences, including the study of the polarization of asteroids to infer properties of asteroids' surfaces. As the founder and lead scientist of the Spacewatch Project on Tucson's Kitt Peak, he was one of the first to study the hazards of near-Earth asteroids. He developed the UA's Space Science Series of conferences and books and wrote more than 10 other books on his own.

Wednesday, July 20, 2011

Symbolic: The probable current state of the Apollo American flags on the Moon, at the very least, bleached of color and degraded into delicate tatters by intense UV radiation. (Scene is the Hadley Rille Valley, landing site of Apollo 15 in 1971 as it might appear 40 years later.)

Paul D. SpudisThe Once & Future MoonSmithsonian Air & Space

Today is the 42nd anniversary of man’s landing on the Moon. The first step on the Moon – the step that “divided history” to use the words of the time – and the planting of the American flag there seems like a lifetime ago. As a matter of fact, it was.

Tomorrow, the Space Shuttle Atlantis will land back at its launch site, ending that program’s 30-year tenure as the centerpiece of America’s space program. That was not a lifetime ago, but a similar sense of loss is evident.

In both cases, the end of a mission series brought upheaval to the space program, as thousands of workers lost their jobs, sold their homes and moved on but not before helping to write an important chapter in America’s history. The end of the Shuttle program and the dismantling of Shuttle infrastructure at Florida’s Cape parallels the dismantling of our national space program.

Ending this major U.S. space program is not like finishing a highway construction project or a bridge, where skilled workers go on to other construction projects. The people that launched Saturn and Shuttle were highly trained – acquiring expert knowledge through years of experience. They cannot be found on the street, but must be carefully assembled and made into a team, trained in their specific specialties, and tested in actual flight experience.

Unlike the end of Apollo, the end of Shuttle finds uncertainty in our national direction in space. Despite the cawing of the flock of “new direction” supporters, a stunning realization is just now sinking in to a bewildered American public: we’re discarding a national capability with no successor – no strategic direction, no vehicle, no path forward. Not even a “flexible” one.

Seven years ago, a positive direction in space was articulated as the Vision for Space Exploration (VSE). In short, it called for the gradual extension of human reach beyond low Earth orbit, starting with a return to the Moon, followed by trips to destinations beyond, including Mars. Despite misinformation in the press, the Vision was not (and still is not) “unaffordable” – its affordability depends on its implementation.

The implementation of the VSE by NASA was predicated on the assumption that the Apollo approach was the best way to establish a new space faring capability. Although such an assumption could be argued, it had the virtue of having an existence proof in that we had done it that way before. A drawback to such an approach is that it opened the program to the criticism that lunar return under the VSE was merely a repeat of Apollo, a canard that wasn’t true then or now.

When Constellation ran into the developmental problems and extra costs that all new programs experience, national leaders became concerned. This concern emanated not from the money being spent (the federal government spends more in 8 hours than NASA spends in a year); the concern was that this new effort appeared to be in support of a “repeat” of Apollo. With few exceptions, most people had never heard the objective of using the Moon to create new space faring capability. Instead, the public repeatedly heard the trite and dismissive “been there, done that” mantra and “We already have six American flags on the Moon,” to quote one notable. And that mis-characterization of the Vision manifested our current direction, i.e., one of no direction.

We discarded both a working transportation system and a strategic path forward in space in exchange for promises of commercial space travel to LEO and dreams of human missions to an asteroid (with nebulous rationale and timetable). Wishing new capabilities into existence without a clear step-by-step path forward would be laughable if it wasn’t so tragic. The administration came to a fork in the road, pondered the direction our national space program could go, and chose a path with no objective or productive program architecture that America could embrace to stay on top of her game.

Over the course of the Apollo program, our astronauts deployed six American flags on the Moon. For forty-odd years, the flags have been exposed to the full fury of the Moon’s environment – alternating 14 days of searing sunlight and 100° C heat with 14 days of numbing-cold -150° C darkness. But even more damaging is the intense ultraviolet (UV) radiation from the pure unfiltered sunlight on the cloth (modal) from which the Apollo flags were made. Even on Earth, the colors of a cloth flag flown in bright sunlight for many years will eventually fade and need to be replaced. So it is likely that these symbols of American achievement have been rendered blank, bleached white by the UV radiation of unfiltered sunlight on the lunar surface. Some of them may even have begun to physically disintegrate under the intense flux.

America is left with no discernible space program while the Moon above us no longer flies a visible U.S. flag.

On the 42nd anniversary of Apollo 11 Commander Neil A. Armstrong's first steps on the moon's surface, Institute of Electrical and Electronics Engineers (IEEE), the world's largest technical professional association, today honored Northrop Grumman (NYSE:NOC) with its IEEE Milestone in Electrical Engineering and Computing award in recognition of the company's work on the lunar module.

The Apollo lunar module, America's first vehicle to enable astronauts to land on the moon and return safely to earth, was designed, developed and built by Grumman Corporation on Long Island. Between 1969 and 1972, six Grumman lunar modules carried 12 astronauts to and from the surface of the moon, including the famed Eagle which first carried Commander Armstrong and Lunar Module Pilot Buzz Aldrin to the Sea of Tranquility. They returned to Earth on July 24, 1969. One module – Aquarius – served as a lifeboat for three astronauts, Jim Lovell, Jack Swigert and Fred Haise, during the ill-fated Apollo 13 mission, which never landed on the moon but returned safely to earth.

The last lunar module to land on the Moon, Apollo 17's Challenger, photographed by Dr. Harrison Schmitt from their lunar rover in December 1972 [AS17-124-20508].

Saturday, July 16, 2011

A wrinkle ridge cross-cuts and deforms an impact crater in northeast Mare Imbrium. The deformed impact crater is about 330 meters in diameter, LROC Narrow Angle Camera (NAC) observation M104540211RE, LRO orbit 565, August 10, 2009; image field of view is 1.7 kilometers. See the full-sized LROC Featured Image, HERE [NASA/GSFC/Arizona State University].

Lillian OstrachLROC News System

Relative age relationships are key to unraveling the geologic history of the Moon. Relative ages reveal the order of geologic events without knowledge of their absolute age. Usually relative ages are determined by the stratigraphic relationships of geologic features - what is on top and what is below.

Stratigraphy is not simply the study of rock layers and layering, it provides geologists with the tool to determine age relations locally, and in some cases globally. Gene Shoemaker and Robert Hackman used some ingenious thinking to describe key stratigraphic markers throughout the Moon's geologic history. But you don't have to be a lunar geologist to understand the significance of stratigraphic relationships. The most obvious stratigraphic relationships on the Moon are the mare basalts embaying (or covering) the older highland terrain.

Sometimes it takes a bit of searching to find clear stratigraphic relationships at the high resolution of the LROC NAC images. Today's Featured Image provides an example of a clear age relation, where an impact crater is cross-cut and deformed by a wrinkle ridge. The deformation of this crater took place in the north-south direction, and distorts the crater from a circular shape to ellipse. Its diameter is ~330 m measured east to west, and in the north-south direction, the crater is only ~300 m wide.

LROC Wide Angle Camera (WAC) monochrome mosaic showing the wrinkle ridge in Mare Imbrium. Although the landscape looks smooth and uniform from Earth, and even at this scale, the LROC Featured Image released July 12 demonstrates otherwise! The asterisk denotes the location of that NAC close-up and the deformed impact crater. See the full-sized LROC context image HERE [NASA/GSFC/Arizona State University].

These observations help us construct a plausible geologic story for this small area. First, the mare basalts erupted and cooled, then the impact crater formed. At some point after the impact event, the wrinkle ridge deformed the crater. However, much time has passed since the impact event, because the crater has no high-reflectance ejecta rays, its walls are smooth, and there are only a few boulders. Alternatively, very little to no time may have passed between crater formation and wrinkle ridge formation because the wrinkle ridge is smooth and also has only a few boulders. So, while parts of the relative age story can be clearly inferred, some details are tricky to fully unravel.

Furthermore, how does the bouldery crater adjacent to the deformed crater fit into this story? There are several options based on the appearance of both craters, but the easiest explanation is that these craters formed at slightly different geologic times because although their rims are rounded and smooth and the craters do not not have ejecta rays, they do have different concentrations of exposed boulders. But why does this adjacent crater have so many more boulders? Boulders are usually formed by impact into a coherent rock layer (e.g., the impact exposes and fractures bedrock). Since the mare regolith is probably only a few meters deep at most, these ~300 m diameter craters would have punched through the regolith layer to expose bedrock. If the two craters are the same age, they should have similar boulder concentrations, but if they are not the same age, we can devise a different geologic story. If we assume that the deformed crater is older than its neighbor, we would expect that the deformed crater would be more eroded. If the neighboring, bouldery crater is younger, then perhaps the boulders surrounding this crater have not had enough time to be worn away by continuous micrometeorite bombardment.

What do you think? Observe the full LROC NAC image and decide whether you can come up with a better geologic story!

On Sunday, July 17, the moon will acquire its second new companion in less than a month. That’s when the second of two probes built by the University of California, Berkeley, and part of NASA’s five-satellite THEMIS mission will drop into a permanent lunar orbit after a meandering, two-year journey from its original orbit around Earth.

The first of the two probes settled into a stable orbit around the moon’s equator on June 27. If all goes well, the second probe will assume a similar lunar orbit, though in the opposite direction, sometime Sunday afternoon. The two spacecraft that comprise the ARTEMIS mission will immediately begin the first observations ever conducted by a pair of satellites of the lunar surface, its magnetic field and the surrounding magnetic environment.

“With two spacecraft orbiting in opposite directions, we can acquire a full 3-D view of the structure of the magnetic fields near the moon and on the lunar surface,” said Vassilis Angelopoulos, principal investigator for the THEMIS and ARTEMIS missions and a professor of space physics at UCLA. “ARTEMIS will be doing totally new science, as well as reusing existing spacecraft to save a lot of taxpayer money.”

“These are the most fully equipped spacecraft that have ever gone to the moon,” added David Sibeck, THEMIS and ARTEMIS project scientist at the Goddard Space Flight Center (GSFC) in Maryland. “For the first time we’re getting a unique, two-point perspective of the moon from two spacecraft, and that will be a major component of our overall lunar research program.”

The transition into a lunar orbit will be handled by engineers at UC Berkeley’s Space Sciences Laboratory (SSL), which serves as mission control both for THEMIS (Time History of Events and Macroscale Interactions during Substorms) and ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun).

The five THEMIS satellites (or probes) were launched by NASA on Feb. 17, 2007 to explore how the sun’s magnetic field and million-mile-per-hour solar wind interact with Earth’s magnetic field on Earth’s leeward side, opposite the sun. Within a year and a half, they had answered the mission’s primary question: Where and how do substorms in the Earth’s magnetosphere – which make the auroras at the north and south poles dance – originate?

The answer: the storms originate deep in the planet’s shadow, about a third of the way to the moon, where magnetic field lines snap, reconnect and unleash a storm of energy that funnels to the poles and makes the atmosphere glow in reds and greens. Large storms can wreak havoc on satellites, power grids and communications systems.

Mission accomplished, the THEMIS team was eager to divert two of the probes to the moon to extend their magnetic field studies farther into space. One key reason was that the two probes most distant from Earth would soon die because, with too much time spent in Earth’s shadow, their solar-powered batteries would discharge.

Side view of the ARTEMIS P1 probe's orbit in 2010 as it cruised around the two Earth-moon Lagrange points. In 2011 it maneuvered into a permanent orbit around the moon [NASA].

“That was an engineering challenge; this is the first mission where we’ve piloted into a lunar orbit spacecraft not designed to go there,” said Daniel Cosgrove, the UC Berkeley engineer who controls the spacecrafts’ trajectories. The probes’ small thrusters, for example, only push down and sideways. The probes are also spinning, which makes maneuvering even more difficult.

Also, last year probe P1 lost a spherical sensor from the end of one of four long wires that protrude from the spacecraft to measure electrical fields in space. The probable cause was a micrometeorite that cut a 10-foot section off of the 82-foot wire and caused it to retract into its original spherical housing, sending the “little black sphere flying through the solar system,” Bester said.

“All five spacecraft have been built by a very talented team with enormous attention to detail,” he said, predicting that the ARTEMIS probes could survive for another 10 years, longer than the three remaining THEMIS probes, which repeatedly fly in and out of Earth’s dangerous Van Allen radiation belt.

Lunar orbit

Once the second probe, P2, is in orbit, the two ARTEMIS satellites will graze the lunar surface once per orbit – approaching within a few tens of kilometers – in a belt ranging 20 degrees above and below the equator while recording electric and magnetic fields and ion concentrations.

“When the moon traverses the solar wind, the magnetic field embedded in the rocks near the surface interacts with the solar wind magnetic field, while the surface itself absorbs the solar wind particles, creating a cavity behind the moon,” Angelopoulos said. “We can study these complex interactions to learn much about the moon as well as the solar wind itself from a unique two-point vantage that reveals for the first time 3-D structures and dynamics.”

Sibeck noted that NASA’s twin STEREO spacecraft, launched in 2006, already provide a 3-D perspective on the sun’s large-scale magnetic fields. “THEMIS and ARTEMIS study the microscale processes, which we now know run the system,” he said.

One goal of the ARTEMIS mission is to look for plasmoids, which are hot blobs of ionized gas or plasma.

“THEMIS found evidence that magnetic reconnection propels hot blobs of plasma both towards and away from the Earth, and we want to find out how big they are and how much energy they carry,” Angelopoulos said. “Plasmoids could be tens of thousands of kilometers across.”

“THEMIS found the cause and now ARTEMIS will study the consequences, which are likely massive and global,” Sibeck said.

The spacecraft also will study the surface composition of the moon by recording the solar wind particles reflected or scattered from the surface and the ions sputtered out of the surface by the wind.

“These measurements can tell us about the properties of the surface, from which we can infer the formation and evolution of the surface over billions of years,” Angelopoulos said.

The two ARTEMIS probes will join NASA’s Lunar Reconnaissance Orbiter, which has been orbiting the moon since 2009 taking high-resolution photographs and looking for signs of water ice. In September, NASA is scheduled to launch two GRAIL (Gravity Recovery and Interior Laboratory) spacecraft to map the moon’s gravitational field, and in 2013, the agency plans to launch LADEE (Lunar Atmosphere and Dust Environment Explorer) to characterize the lunar atmosphere and dust environment.

“ARTEMIS will provide context for the LADEE mission,” Sibeck said.

Three other non-functioning satellites remain in orbit around the moon: two subsatellites of Japan’s lunar orbiter, Kaguya, which was guided to a crash on the surface in 2009; and India’s Chandrayaan-1, which lost communication with Earth that same year. China’s second lunar orbiter, Chang’e 2, left the moon for interplanetary space on June 8.

The discovery of impact melt deposits on the Moon is nothing new - large impact melt deposits were observed in Apollo era images. However, the high-resolution LROC NAC images provide views of impact melt flows that are much more widespread, beautiful, and complex than lunar geologists imagined! Melt deposits are not limited to crater interiors, impact melt is also observed on crater walls and outside of the crater - we've frequently focused on such occurrences in past Featured Images. Today's Featured Image shows the distal portion (a few hundred meters) of a several kilometer-long impact melt deposit that flowed away from the crater rim across the continuous ejecta blanket. There are even some ~5 to 10 m diameter boulders entrained within the impact melt flow.

The unnamed Copernican-aged crater, ~3 km in diameter, has an impressive and complex set of impact melt deposits. There are regions where the impact melt has eroded along parts of the flow, usually along what appear to be melt flow fronts. In some places, the erosion gives an illusion of waves across the landscape, which may reflect the process of impact melt deposition in stages. There are also places within the flow where breakout lobes flowed over the surface of the larger impact melt deposit.

A distinct lobe of impact melt within the larger melt sheet. How did this feature form? LROC NAC M159631206L & R; source crater below and beyond field of view. View the full-size LROC image HERE [NASA/GSFC/Arizona State University].

The presence of a superposed lobe might suggest that there were multiple, distinct phases of deposition. However, the formation of an impact crater ~3 km in diameter is a near-instantaneous event, taking no more than a minute or two to form and emplace both the ejecta blanket and splash out impact melt from the crater interior. It is likely that the impact melt was deposited in a very short amount of time, probably in a quick succession of multiple stages. The lobe pictured above suggests that impact melt was deposited at slightly different times and/or upstream damming occurred that was then followed by a breakout (similar mechanism to basalt flows in Hawaii). Or, an alternate idea is that it may have formed through coalescence of melt while the melt was still fluid and flowed, following local slope changes, until the melt cooled. For the moment, we just don't know. Additional analysis, such as creating a DTM, would be useful because we could make slope measurements and make estimates on the amount of potential energy needed for a liquid impact melt to flow as we observe here.